two pressure cooker devices loaded up with deadly shrapnel designed to maim anyone standing by and jim avila has more. it's not hard to find out how to build one. >> reporter: it's not. investigators are learning more about the anatomy of the bombs and abc news confirming the common cooking appliance used in their construction was a midsize fager brand pressure cooker. unfortunately, the pot maker sells 50,000 a year of those in the united states. this is what remains of what investigators believe could be the crude but effective bomb used in boston. the american military knows them well. the pressure cooker bomb. homemade and designed to maim and kill. this video of military units detonating one in afghanistan posted on youtube. this one found on the internet from the streets of nepal. so common the department of defense handbook on spotting roadside bombs warns soldiers and marines to be on the lookout for that innocent pressure cooker and publications all over the internet teach the construction of a bomb made from mom's kitchen, why so popular? because pressure cookers seal so tigh